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| United States Patent |
5,109,064
|
|
Wakabayashi
, et al.
|
April 28, 1992
|
Curable composition
Abstract
A curable composition formed from:
(A) a copolymer that has silicon-containing functional groups capable of
crosslinking by forming siloxane bonds and molecular chain containing:
(1) at least one monomeric unit selected from the group consisting of short
chain alkyl acrylate esters and short chain alkyl methacrylate esters,
said short chain alkyl groups having 1 to 8 carbon atoms, and
(2) at least one monomeric unit selected from the group consisting of long
chain alkyl acrylate esters and long chain alkyl methacrylate esters, said
long chain alkyl groups having 10 to 30 carbon atoms;
wherein the total amount of the monomeric units (1) and (2) in said
copolymer is at least 50 weight %, and
(B) an oxyalkylene polymer having silicon-containing functional groups that
are capable of crosslinking by forming siloxane bonds; and
(C) a curing accelerator,
wherein copolymer (A) is present in an amount of 5 to 5,000 parts by weight
per 100 parts by weight of oxyalkylene polymer (B), and curing acelerator
is present in an amount of 0.1 to 20 parts by weight per 100 parts by
weight of the sum of copolymer (A) and oxyalkylene polymer (B).
| Inventors:
|
Wakabayashi; Hiroshi (Kobe, JP);
Isayama; Katsuhiko (Kobe, JP)
|
| Assignee:
|
Kanegafuchi Kagaku Kogyo Kabushiki Kaisha (Osaka, JP)
|
| Appl. No.:
|
463910 |
| Filed:
|
January 16, 1990 |
Foreign Application Priority Data
| Oct 29, 1986[JP] | 61-257628 |
| Current U.S. Class: |
525/100; 525/404 |
| Intern'l Class: |
C08L 083/14 |
| Field of Search: |
525/100,404
|
References Cited
U.S. Patent Documents
| 5030691 | Jul., 1991 | Kohmitsu | 525/100.
|
Primary Examiner: Marquis; Melvyn I.
Assistant Examiner: Dean, Jr.; R.
Attorney, Agent or Firm: Armstrong, Nikaido, Marmelstein, Kubovcik & Murray
Parent Case Text
This application is a continuation of application Ser. No. 246,102 filed
Sep. 19, 1988, now abandoned, which is a continuation-in-part of
application Ser. No. 112,979, filed Oct. 27, 1987, now abandoned.
Claims
What is claimed is:
1. A curable composition comprising:
(A) a copolymer having silicon-containing functional groups capable of
crosslinking by forming siloxane bonds and molecular chain containing:
(1) at least one monomeric unit selected from the group consisting of short
chain alkyl acrylate esters and short chain alkyl methacrylate esters,
said short chain alkyl groups having 1 to 8 carbon atoms, and
(2) at least one monomeric unit selected from the group consisting of long
chain alkyl acrylate esters and long chain alkyl methacrylate esters, said
long chain alkyl groups having 10 to 30 carbon atoms;
wherein the total amount of the monomeric units (1) and (2) in said
copolymer is at least 50 weight %, and
(B) an oxyalkylene polymer having silicon-containing functional groups that
are capable of crosslinking by forming siloxane bonds; and
(C) a curing accelerator, wherein copolymer (A) is present in an amount of
5 to 5,000 parts by weight per 100 parts by weight of oxyalkylene polymer
(B), and curing accelerator is present in an amount of 0.1 to 20 parts by
weight per 100 parts by weight of the sum of copolymer (A) and oxyalkylene
polymer (B).
2. A curable composition according to claim 1, wherein a monomeric unit (1)
is represented by formula (I)
##STR20##
where R.sup.1 is an alkyl group having 1 to 8 carbon atoms, and R.sup.2 is
a hydrogen atom or a methyl group; and a monomeric unit (2) is represented
by formula (II)
##STR21##
where R.sup.2 is the same as defined above, and R.sup.3 is an alkyl group
having 10 to 30 carbon atoms.
3. A curable composition according to claim 1, wherein a ratio of the
monomeric units (1):(2) is 95:4 to 40:60.
4. A curable composition according to claim 1, wherein a copolymer (A) has
500 to 100,000 of number average molecular weight.
5. A curable composition according to claim 1, wherein an oxyalkylene
polymer (B) has a repeating unit of formula --R.sup.7 --O--, wherein
R.sup.7 is a divalent hydrocarbon group having 1 to 8 carbon atoms.
6. A curable composition according to claim 1, wherein a curing accelerator
is selected from the group consisting of an organic tin compounds, organic
titanate compounds, acid phosphate esters, reaction products of acid
phosphate esters and amines, saturated or unsaturated polycarboxylic
acids, and acid anhydrides of saturated or unsaturated polycarboxylic
acids.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a curable composition containing two or
more curable polymers. More specifically, it relates to a curable
composition that contains an acrylic acid ester and/or methacrylic acid
ester based curable polymer, and a curable oxyalkylene polymer, and which
has superior mechanical properties, transparency, storage stability and
weather resistance. In the following description, an acrylic acid ester
and/or methacrylic acid ester is referred to as a (meth)acrylic acid
ester.
The present inventors previously found that a (meth)acrylic acid ester
based polymer having silicon-containing functional groups that are capable
of crosslinking by forming siloxane bonds either at terminals or in side
chains (this type of silicon-containing functional groups is hereinafter
referred to as reactive silicon functional groups) crosslinks at normal
temperatures by reacting with moisture, particularly the moisture in the
air, to form a network structure, thereby yielding a cured product having
good properties such as high weather resistance, hardness and water
resistance. The present inventors accomplished an invention based on this
finding and filed a Japanese patent application (OPI) No. 36395/79
(hereinafter OPI is referred to as unexamined published Japanese patent
application).
Oxyalkylene polymers having reactive silicon functional groups have been
proposed in many patents such as Japanese Patent Publication Nos.
36319/70, 12154/71, 32673/74, and Japanese Patent Application (OPI) Nos.
156599/75, 73561/76, 6096/79, 82123/80, 123620/80, 125121/80, 131022/80,
135135/80 and 137129/80.
The prior art (meth)acrylic acid ester based polymers containing reactive
silicon functional groups have superior performance but, on the other
hand, the cured products thereof are brittle and even with resin
compositions having low glass transition points, the cured products have
unacceptable physical properties such as low tensile strength and low
percent elongation at break.
The cured products of oxyalkylene polymers having reactive silicon
functional groups possess better tensile characteristics but there still
is the need to achieve further improvements in their characteristics. In
addition, all of the known oxyalkylene polymers having reactive silicon
functional groups are defective in their performance in that because of
the structure of the backbone chains and other factors, they do not
possess satisfactory weather resistance and fail to produce adequate bond
to various substrates.
Several methods have been proposed as techniques that are capable of
eliminating the defects of the prior art oxyalkylene polymers having
reactive silicon functional groups. In the method disclosed in U.S. Pat.
No. 4,593,068, an oxyalkylene polymer having reactive silicon functional
groups are blended with a (meth)acrylic acid ester based polymer
optionally having reactive silicon functional groups. This method is
effective to some extent for the purpose of improving the initial
performance of the oxyalkylene polymer having reactive silicon functional
groups but it is not easy to obtain sufficiently compatible composition
having good transparency and good storage stability.
Methods are also known in which (meth)acrylic acid ester based monomers are
modified by being polymerized in the presence of oxyalkylene polymers
having reactive silicon functional groups (see U.S. Ser. No. 759,877, and
U.S. Pat. No. 4,618,656 and 4,618,653). These methods are capable of
improving properties such as storage stability but they suffer from the
disadvantage of reduced production rate, in particular, low production
rate per the capacity of the polymerization vessel since the product
obtained by preliminary polymerization and reaction must be charged into
another polymerization vessel for performing the polymerization of the
necessary monomers. Furthermore, if one wants to make a modified
oxyalkylene polymer having a different monomer/oxyalkylene polymer ratio,
it is necessary to perform polymerization in the presence of the
oxyalkylene polymer each time such need arises, which is quite
troublesome. It has therefore been desired to attain the intended results
by mere blending.
SUMMARY OF THE INVENTION
An object, therefore, of the present invention is to provide a composition
that yields a cured product having improved mechanical properties (e.g.
tensile characteristics), transparency, storage stability and weather
resistance as compared with the cured products of (meth)acrylic acid ester
based polymers or oxyalkylene polymers having reactive silicon functional
groups or compositions containing (meth)acrylic acid ester based polymer
and oxyalkylene polymer.
With a view to eliminating the defects mentioned above of the prior art
(meth)acrylic acid ester based polymers or oxyalkylene polymers having
reactive silicon functional groups or compositions containing these two
polymers, the present inventors undertook intensive studies and found that
these defects can be effectively eliminated by a composition having an
alkyl (meth)acrylate ester based polymer having a long-chain alkyl group
and an oxyalkylene polymer.
The present invention, therefore, relates to a curable composition which
comprises:
(A) a copolymer that has silicon-containing functional groups capable of
crosslinking by forming siloxane bonds and molecular chain containing:
(1) at least one monomeric unit selected from the group consisting of short
chain alkyl acrylate esters and short chain alkyl methacrylate esters,
said short chain alkyl group having 1 to 8 carbon atoms, and
(2) at least one monomeric unit selected from the group consisting of long
chain alkyl acrylate esters and long chain alkyl methacrylate esters, said
long chain alkyl group having 10 to 30 carbon atoms;
wherein a total amount of the monomeric units (1) and (2) in said copolymer
is 50 weight % or more, and
(B) an oxyalkylene polymer having silicon-containing functional groups that
are capable of crosslinking by forming siloxane bonds; and
(C) a curing accelerator, wherein copolymer (A) is present in an amount of
5 to 5,000 parts by weight per 100 parts by weight of oxyalkylene polymer
(B), and curing accelerator is present in an amount of 0.1 to 20 parts by
weight per 100 parts by weight of the sum of copolymer (A) and oxyalkylene
polymer (B).
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a graph showing the tensile strength and elongation at break of
sheet as a function of the ratio at which copolymer (A) prepared in
Synthesis Example 2 was mixed with polyoxypropylene (B) prepared in
Synthesis Example 8; and
FIG. 2 is a graph showing the tensile strength and elongation at break of
sheet as a function of the ratio at which copolymer (A) prepared in
Synthesis Example 3 was mixed with polyoxypropylene (B) prepared in
Synthesis Example 8.
DETAILED DESCRIPTION OF THE INVENTION
The composition of the present invention provides a cured product that
exhibits improved mechanical properties (e.g. tensile characteristics),
weather resistance and good bond to various substrates as compared with
the prior art (meth)acrylate ester based polymers or oxyalkylene based
polymers containing reactive silicon functional groups. Further, whether
it is in a cured or uncured state, this composition remains highly
transparent and stable over time (i.e., even if it is stored for a
prolonged time, it will not become turbid or separate into two layers) as
compared with the prior art composition comprising (meth)acrylate ester
based polymer and oxyalkylene based polymer, as disclosed in U.S. Pat. No.
4,593,068. It is not completely clear why the composition of the present
invention affords such advantages, but presumably this is because of the
crosslinking reaction between reactive silicon functional groups that
occurs subsequent to the solubilization and compatibilization of the
alkylene oxide polymer caused by the long-chain alkyl group in the alkyl
(meth)acrylate ester based polymer employed in the present invention. In
other words, the advantages of the composition of the present invention
would result from the formation of a certain type of IPN (interpenetrating
polymer network) structure (see D. Klempner and K. C. Frisch, "Polymer
Alloys" vol. 2, Plenum Press, New York, 1980, at p. 338)).
The curable copolymer which is used as component (A) in the present
invention [this copolymer is hereinafter referred to as copolymer (A)]
consists substantially of an alkyl (meth)acrylate ester monomeric unit (1)
having a short chain alkyl group with 1 to 8 carbon atoms and an alkyl
(meth)acrylate ester monomeric unit (2) having a long chain alkyl group
with 10 to 30 carbon atoms. The monomeric unit (1) is represented by
general formula (I):
##STR1##
where R.sup.1 is a short chain alkyl group having 1 to 8 carbon atoms; and
R.sup.2 is a hydrogen atom or a methyl group. The monomeric unit (2) is
represented by general formula (II):
##STR2##
where R.sup.2 is the same as defined above; and R.sup.3 is a long chain
alkyl group having 10 to 30 carbon atoms.
Examples of R.sup.1 in the general formula (I) include alkyl groups having
1 to 8, preferably 1 to 4, more preferably 1 and 2 carbon atoms such as
methyl, ethyl, propyl, n-butyl, t-butyl and 2-ethylhexyl. The alkyl groups
as R.sup.1 may be present either alone or in admixture.
Examples of R.sup.3 in the general formula (II) include long chain alkyl
groups having 10 to 30 preferably 10 to 20, carbon atoms such as lauryl,
tridecyl, cetyl, stearyl and behenyl (alkyl having 22 carbon atoms). As in
the case of R.sup.1, the alkyl groups represented by R.sup.3 may be
present either alone or in admixture of two or more alkyls such as, for
example, alkyls having 12 and 13 carbon atoms.
The molecular chain of the copolymer (A) is substantially composed of the
monomeric units (1) and (2). The term "substantially" means that the sum
of the monomeric units (1) and (2) present in copolymer (A) exceeds 50 wt
% of said copolymer. The sum of the two monomeric units is preferably at
least 70 wt % of the copolymer (A).
The weight ratio of monomeric unit (1) to (2) is preferably in the range of
95:5 to 40:60, more preferably in the range of 90:10 to 60:40.
The copolymer (A) may contain monomeric units in addition to the monomeric
units (1) and (2) and examples of such optionally present monomeric units
include: carboxylic-containing monomers such as acrylic acid and
methacrylic acid; amide-containing monomers such as acrylamide,
methacrylamide, N-methylol acrylamide and N-methylol methacrylamide;
epoxy-containing monomers such as glycidyl acrylate and glycidyl
methacrylate; amino-containing monomers such as diethylaminoethyl
acrylate, diethylamino ethyl methacrylate and aminoethyl vinyl ether; and
monomeric units derived from such compounds as acrylonitrile, styrene,
.alpha.-methylstyrene, alkylvinyl ether, vinyl chloride, vinyl acetate,
vinyl propionate, and ethylene.
From the viewpoint of ease of handling, the copolymer (A) preferably has a
number average molecular weight of 500 to 100,000.
The reactive silicon functional groups in copolymer (A), or the
silicon-containing functional groups that are capable of crosslinking by
forming siloxane bonds, are well known in the art and are characterized by
their ability to crosslink even at room temperature. Typical examples of
such reactive silicon functional groups are represented by general formula
(III):
##STR3##
where R.sup.4 is a substituted or unsubstituted monovalent organic group
having 1 to 20 carbon atoms or a triorganosiloxy group; X which may be of
a different or same is a hydroxyl group or a hydrolyzable group; a is an
integer of 0, 1 or 2; b is an integer of 0, 1, 2 or 3, with proviso that
when a is 2, b is not 3; and m is an integer of 0 to 18.
Reactive silicon functional groups which are preferred for such reasons as
economy are represented by general formula (IV):
##STR4##
where R.sup.4 and X are the same as defined above; n is an integer of 0, 1
or 2.
In order to ensure satisfactory curability, the copolymer (A) preferably
contains at least 1, more preferably at least 1.1, and most preferably at
least 1.5 units of reactive silicon functional groups on average.
Preferably, the copolymer (A) contains an apparent number average
molecular weight of 300 to 4,000 per reactive silicon functional group.
Specific examples of the hydrolyzable group in formula (III) include a
halogen atom, a hydrogen atom, an alkoxy group, an acyloxy group, a
ketoximate group, an amino group, an amido group, an aminoxy group, a
mercapto group and an alkenyloxy group. Among these examples, alkoxy
groups such as methoxy and ethoxy are preferred since they will undergo
hydrolysis under mild conditions.
Specific examples of R.sup.4 in formula (III) include alkyl groups such as
methyl and ethyl, cycloalkyl groups such as cyclohexyl, aryl groups such
as phenyl, and aralkyl groups such as benzyl, wherein said cyclohexyl,
phenyl or benzyl group may optionally be substituted with halogen. In
formula (III) or (IV), R.sup.4 may be a triorganosiloxy group represented
by the following formula:
(R.sup.4).sub.3 SiO--
where R.sup.4 is the same as defined above. A particularly preferred
example of R.sup.4 in formula (III) or (IV) is methyl.
The copolymer (A) used in the present invention can be prepared by vinyl
polymerization, for example, vinyl polymerization initiated by radical
reaction in solution polymerization, bulk polymerization or any other
conventional procedures of polymerization of monomers that provide the
units represented by formulae (I) and (II).
The polymerization is carried out by reacting the necessary monomers and
optional additives such as a radical initiator at 50.degree. to
150.degree. C., preferably in the presence of a chain transfer agent, such
as n-dodecyl mercaptan or t-dodecyl mercaptan, which is optionally
employed in order to attain a copolymer (A) having a number average
molecular weight of 500 to 100,000. A solvent may or may not be used and
if it is used, it is preferably selected from among non-reactive solvents
such as ethers, hydrocarbons and acetate esters.
Reactive silicon functional groups may be introduced into the copolymer (A)
by various methods such as: (a) a method wherein a compound such as
CH.sub.2 .dbd.CHSi(OCH.sub.3).sub.3 that has polymerizable unsaturated
bonds and reactive silicon functional groups is added to monomers that
provide the units represented by formulae (I) and (II) and the individual
monomers are copolymerized; and (b) a method wherein a compound such as
acrylic acid having polymerizable unsaturated bonds and reactive
functional groups (hereinafter abbreviated as Y group) is added to
monomers that provide the units represented by formulae (I) and (II) and
thereafter, the resulting copolymer is reacted with a compound that has
functional silicon groups and functional groups capable of reacting with Y
group (the latter functional groups are hereinafter abbreviated as Y'
functional group), such as a compound having both an isocyanate group and
the group --Si(OCH.sub.3).sub.3.
An example of the compound having polymerizable unsaturated bonds and
reactive silicon functional groups may be represented by general formula
(V):
##STR5##
where R.sup.5 is a residual organic group having a polymerizable
unsaturated bond; and R.sup.4, X, a, b and m are each the same as defined
above. A preferred example of the compound of formula (V) is represented
by general formula (VI):
##STR6##
where R.sup.2, X and n are each the same as defined above; Q is a divalent
organic group such as --COOR.sup.6 -- (where R.sup.6 is a divalent
alkylene group having 1 to 6 carbon atoms such as --CH.sub.2 -- or
--CH.sub.2 CH.sub.2 --), --CH.sub.2 C.sub.6 H.sub.5 CH.sub.2 CH.sub.2 --,
--CH.sub.2 OCOC.sub.6 H.sub.4 COO(CH.sub.2).sub.3 --;
and p is 0 or 1.
Specific examples of the compounds represented by formulae (V) and (VI) are
listed below:
##STR7##
These silane compounds can be synthesized by various methods, one of which
comprises reacting a compound such as acetylene, allyl acrylate, allyl
methacrylate or diallyl phthalate with a compound such as methyl
dimethoxysilane or methyl dichlorosilane in the presence of a catalyst
containing a transition metal of Group VIII of the Periodic Table. An
effective catalyst may be a compound of a metal of Group VIII selected
from platinum, rhodium, cobalt, palladium and nickel. Particularly
preferred compounds are platinum based, such as platinum black,
chloroplatinic acid, platinum alcohol compound, platinum-olefin complex,
platinum-aldehyde complex, and platinum-ketone complex.
Method (b) that can be employed to introduce reactive silicon functional
groups into copolymer (A) is hereinafter described with reference to an
illustrative example. While various combinations of groups may be employed
as Y and Y' groups, a vinyl group and a hydrosilicon group (H-Si-) may
respectively be used. The Y and Y' groups are capable of bonding to each
other through a hydrosilylation reaction. Examples of the compound that
has not only a vinyl group as Y group but also a polymerizable unsaturated
bond are listed below: allyl acrylate, allyl methacrylate, diallyl
phthalate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate,
1,5-pentanediol diacrylate, 1,5-pentanediol dimethacrylate, 1,6-hexanediol
diacrylate, 1,6-hexanediol dimethacrylate, polyethylene glycol diacrylate,
polyethylene glycol dimethacrylate, polypropylene glycol diacrylate,
polypropylene glycol dimethacrylate, divinylbenzene, and butadiene.
A typical example of the compound having not only a hydrosilicon group as
Y' group but also a reactive silicon functional group may be a hydrosilane
compound represented by general formula (VII):
##STR8##
where R.sup.4, X, a, b and m are each the same as defined above.
The hydrosilane compounds of formula (VII) may be exemplified but are in no
way limited by the following: halogenated silanes such as trichlorosilane,
methyldichlorosilane, dimethylchlorosilane and
trimethylsiloxydichlorosilane; alkoxysilanes such as trimethoxysilane,
triethoxysilane, methyl dimethoxysilane, phenyl dimethoxysilane, and
1,3,3,5,5,7,7-heptamethyl-1,1-dimethoxytetrasiloxane; acyloxysilanes such
as methyl diacetoxysilane and trimethylsiloxymethyl acetoxysilane;
ketoximate silanes such as bis(dimethylketoximate)methylsilane, bis
(cyclohexylketoximate)methylsilane, and
bis(diethylketoximate)trimethylsiloxysilane; hydrosilanes such as
dimethylsilane, trimethylsiloxysilane and
1,1-dimethyl-3,3-dimethyldisiloxane; and alkenyloxysilanes such as methyl
di(isopropenyloxy)silane.
For reaction with a C.dbd.C bond, the hydrosilane compound may be used in
any amount with respect to the C.dbd.C bond but is preferably used in an
amount of 0.5 to 2.0 moles per mole of the C.dbd.C bond. A greater amount
of silane may be employed, however, any excess silane will be simply
recovered as unreacted hydrosilane.
The reaction between the hydrosilane compound and the C.dbd.C bond requires
a catalyst made of the aforementioned compound of a transition metal of
group VIII. This hydrosilylation reaction is accomplished at any
temperature between 50.degree. and 130.degree. C. and the reaction time
generally ranges from about 1 to 10 hours.
Halogenated silanes which are inexpensive and highly reactive stock
materials may be readily employed as hydrosilane compounds.
If halogenated silanes are used, the resulting copolymer (A), when exposed
to the air, will rapidly cure at normal temperatures while releasing
hydrogen chloride. Since the released hydrogen chloride will produce an
irritating odor or cause corrosion, the cured product can be used in only
limited practical applications. It is therefore preferable to convert the
bonded halogen atom to a suitable hydrolyzable group or hydroxyl group.
Illustrative hydrolyzable groups include alkoxyl, acyloxy, aminoxy,
phenoxy, thioalkoxy and amino groups.
Specific methods for converting a halogen atom to an alkoxy group are
described below:
(1) reacting the halogen atom with an alcohol such as methanol, ethanol,
2-methoxyethanol, sec-butanol or tert-butanol, or with a phenol;
(2) reacting the halogen atom with an alkali metal salt of an alcohol or a
phenol; and
(3) reacting the halogen atom with an alkyl orthoformate such as methyl
orthoformate or ethyl orthoformate.
Specific methods for converting a halogen atom to an acyloxy group are
described below:
(1) reacting the halogen atom with a carboxylic acid such as acetic acid,
propionic acid or benzoic acid; and
(2) reacting the halogen atom with an alkali metal salt of a carboxylic
acid.
Specific methods for converting a halogen atom to an aminoxy group are
described below:
(1) reacting the halogen atom with a hydroxylamine such as
N,N-dimethylhydroxylamine, N,N diethylhydroxylamine,
N,N-methylphenylhydroxylamine or N-hydroxypyrrolidine; and
(2) reacting the halogen atom with an alkali metal salt of a hydroxylamine.
Specific methods for converting a halogen atom to an amino group are
described below:
(1) reacting the halogen atom with a primary or secondary amine such as
N,N-dimethylamine or N,N-methylphenylamine or pyrrolidine; and
(2) reacting the halogen atom with an alkali metal salt of a primary or
secondary amine.
Specific methods for converting a halogen atom to a thioalkoxy group are
listed below:
(1) reacting the halogen atom with a thioalcohol such as ethyl mercaptan,
or with a thiophenol; and
(2) reacting the halogen atom with an alkali metal salt of a thioalcohol or
a thiophenol.
As described above, the halogen atom on the silyl group introduced into the
C.dbd.C bond by hydrosilylation reaction can be converted to another
hydrolyzable group. In addition, other groups such as alkoxy or acyloxy in
the introduced silyl group may also be converted to another hydrolyzable
group (e.g. amino or aminoxy) or a hydroxyl group.
When hydrolyzable groups on the silyl group that is directly introduced by
hydrosilylation reaction are converted to other hydrolyzable groups, a
temperature in the range of 50.degree. to 150.degree. C. is suitably
employed. This conversion reaction may be performed with or without a
solvent. If a solvent is to be used, an inert solvent such as an ether, a
hydrocarbon or an acetate ester is used with advantage.
An oxyalkylene polymer having reactive silicon functional groups in its
molecule [this polymer is hereinafter referred to as oxyalkylene polymer
(B)] is also used in the present invention, and examples of oxyalkylene
polymer (B) are proposed in many patents such as Japanese Patent
Publication Nos. 36319/70, 12154/71 and 32673/74, as well as in Japanese
Patent Application (OPI) Nos. 156599/75, 73561/76, 6096/79, 82123/80,
123620/80, 125121/80, 131022/80, 135135/80 and 137129/80.
The molecular chain of oxyalkylene polymer (B) preferably has a recurring
unit that is represented by the general formula:
--R.sup.7 --O--
where R.sup.7 is a divalent hydrocarbon group having 1 to 8 carbon atoms,
preferably a hydrocarbon group having 3 or 4 carbon atoms. It is
preferable that the sum of the recurring units: --R.sup.7 --O-- in
oxyalkylene polymer (B) exceeds 50 wt %, specifically 70 wt % of said
polymer. Specific
##STR9##
The molecular chain of the oxyalkylene polymer may be composed of recurring
units of a single type or two or more different types. A particularly
preferred example of
##STR10##
The reactive silicon functional groups in the oxyalkylene polymer (B) are
the same as already defined.
In order to attain adequate curability, the oxyalkylene polymer (B)
preferably contains at least 1, more preferably at least 1.1, and most
preferably at least 1.5, reactive silicon functional groups, on average.
Such reactive silicon functional groups are preferably present at
terminals of the molecular chain of the oxyalkylene polymer (B).
The oxyalkylene polymer (B) has a number average molecular weight which
preferably ranges from 500 to 30,000, more preferably from 3,000 to
15,000. Oxyalkylene polymers (B) may be used either alone or in
combination.
The oxyalkylene polymer (B) may be prepared by performing an addition
reaction between a hydrogenated silicon compound of formula (VII) and a
polyester containing an olefin group represented by general formula
(VIII):
##STR11##
where R.sup.8 is a hydrogen atom or a monovalent organic group having 1 to
20 carbon atoms; R.sup.9 is a divalent organic group having 1 to 20 carbon
atoms; c is an integer of 0 or 1, in the presence of a catalyst made of a
metal of group VIII such as platinum.
Other methods for preparing the oxyalkylene polymer (B) are described
below:
(1) reacting a hydroxyl-terminated polyoxyalkylene with a polyisocyanate
compound such as toluene diisocyanate to form an isocyanate-terminated
alkylene oxide polymer, and subsequently reacting the terminal isocyanate
group with W group in a silicon compound represented by general formula
(IX):
##STR12##
where W is an active hydrogen containing group selected from among a
hydroxyl group, a carboxyl group, a mercapto group and an amino group
(primary or secondary); and n, R.sup.4, R.sup.9 and X are each the same as
defined above;
(2) performing an addition reaction between an olefin group in an
olefin-containing polyoxyalkylene represented by formula (VIII) and a
mercapto group in a silicon compound of formula (IX) where W is a mercapto
group; and
(3) reacting a hydroxyl group in a hydroxylterminated polyoxyalkylene with
a compound represented by general formula (X):
##STR13##
where R.sup.4, R.sup.9, X and n are each the same as defined above. It
should, however, be noted that the oxyalkylene polymer (B) may be prepared
by other methods.
In the preparation of oxyalkylene polymer (B) part or all of X groups in
the reactive silicon functional group may be converted to other
hydrolyzable groups or a hydroxyl group. If X group is a halogen atom or
hydrogen atom, it is preferably converted to an alkoxy, acyloxy, aminoxy,
alkenyloxy, hydroxyl group or some other group. In formula (VIII), R.sup.8
is a hydrogen atom or a substituted or unsubstituted monovalent organic
group having 1 to 20 carbon atoms, and is preferably a hydrogen atom or a
hydrocarbon group, with the former being particularly preferred. In
formula (VIII), R.sup.9 is a divalent organic group having 1 to 20 carbon
atoms and is preferably --R.sup.10 --, --R.sup.10 OR.sup.10 --,
##STR14##
wherein R.sup.10 is a hydrocarbon group having 1 to 10 carbon atoms, with
a methylene group being particularly preferred. The alkylene oxide polymer
containing an olefin group of formula (VIII) may be prepared by various
methods such as the one disclosed in Unexamined Published Japanese Patent
Application (OPI) No. 6097/79 and a method in which an epoxy compound such
as ethylene oxide or propylene oxide is polymerized with an
olefin-containing epoxy compound such as allyl glycidyl ether producing an
alkylene oxide polymer having an olefin group in a side chain.
Examples of the curing accelerator (C) to be used in the present invention
include, for example, organotin compounds, acidic phosphate ester
compounds, the products of reaction between acidic phosphate ester
compounds and amines, saturated or unsaturated polyvalent carboxylic acids
or acid anhydrides thereof, and organic titanate compounds.
Illustrative organotin compounds include dibutyltin dilaurate, dioctyltin
dimaleate, dibutyltin phthalate, tin octylate and dibutyltin methoxide.
The acidic phosphate ester compounds are, those containing a portion
represented by
##STR15##
and may be more specifically represented by
##STR16##
where d is 1 or 2; and R is an organic residual group. Examples of such
organic acidic phosphate esters are listed below:
##STR17##
Illustrative organic titanates are titanate esters such as tetrabutyl
titanate, tetraisopropyl titanate and triethanolamine titanate.
In the curable composition of the present invention, 5 to 5,000 parts by
weight of copolymer (A) are preferably used per 100 parts by weight of the
oxyalkylene polymer (B) since if the proportions of the (A) and (B) are
within this range, a significant improvement is attained in the
characteristic of the curable composition. More preferably, 5 to 2,000
parts by weight of copolymer (A) are used per 100 parts by weight of the
oxyalkylene polymer (B), with suitable weight proportions of (A) and (B)
being selected in accordance with the intended use and performance of the
curable composition.
The curing accelerator is preferably used in an amount of 0.1 to 20 parts
by weight, more preferably 0.5 to 10 parts by weight, per 100 parts by
weight of the sum of copolymer (A) and oxyalkylene polymer (B).
As mentioned earlier in this specification, the curable composition of the
present invention is characterized by:
(1) solubilization and compatibilization of the oxyalkylene polymer (B) by
the action of the long-chain alkyl group in side chains in the copolymer
(A); and
(2) subsequent fixation of an IPN structure due to the three-dimensional
network produced by the reaction of reactive silicon functional groups in
the compatibilized state.
On account of these characteristics, the curable composition of the present
invention exhibits the following superior performance:
(1) It displays tensile characteristics (e.g., elongation and tensile
strength), adhesion strength, impact resistance, weather resistance, water
resistance and solvent resistance, which are better than those anticipated
from the performance and proportions of the individual polymers;
(2) Compared with the prior art composition which comprises an oxyalkylene
polymer and a (meth)acrylate ester based polymer containing reactive
silicon functional groups (U.S. Pat. No. 4,593,068), the curable
composition of the present invention is highly stable during storage as
manifested by the absence of turbidity and separation into two layers; and
(3) Because of high compatibility between the two polymers, they may be
blended at varying portions over a wide range so as to choose an
appropriate property such as hardness and this enables engineering
materials having broad-spectrum performance.
The curable composition of the present invention may further contain
various components such as fillers, plasticizers and conventional
additives.
Usable fillers include ground calcium carbonate, precipitated calcium
carbonate, gelatinous calcium carbonate, kaolin, talc, silica, titanium
oxide, aluminum silicate, magnesium oxide, zinc oxide and carbon black.
Usable plasticizers include dioctyl phthalate, butylbenzylphthalate,
chlorinated paraffin and epoxidized soybean oil.
Examples of the conventional additives that can be used include antisag
agents such as hydrogenated castor oil and organic bentonite, coloring
agents and antioxidants.
The curable composition of the present invention is useful for many
purposes such as adhesives, pressure-sensitive adhesives, paints, film
water proofing agents, sealant compositions, templating materials, casting
rubber materials and foaming materials.
If the curable composition of the present invention is to be used as a
sealing material, a curing catalyst of the type described above is mixed
with a formulation of the necessary components in a moisture-free
condition and the blend can be stored for a prolonged period without
degradation. When the blend is exposed to aerial moisture as required, it
cures rapidly to form a good rubber elastomer. In other words, the curable
composition of the present invention can be used as a one-component
elastomeric sealing material which displays good weather resistance,
transparency and tensile elongation.
If the curable composition of the present invention is used as a paint, it
exhibits a much higher tensile elongation and weather resistance than is
usually anticipated and displays excellent characteristics for use as a
highly elastic paint in construction applications, or as a primer or a
waterproofing agent in concrete structures.
If the curable composition of the present invention is used as a film
waterproofing agent, it exhibits a good balance between breaking strength
and elongation while affording high durability and good resistance to
water, so it is less sensitive to blistering and spalling than the
products prepared by existing techniques.
If the curable composition of the present invention is used as an adhesive,
it exhibits high bond strength, in particular, a good balance between
peeling bond strength and shearing bond strength, and therefore holds
promise for application as an adhesive in building structures.
The following synthesis examples and working examples are given for the
purpose of further illustrating the present invention but are in no way to
be taken as limiting.
SYNTHESIS EXAMPLES 1-7
Xylene (for its amount, see Table 1 below) was heated at 110.degree. C. To
the heated xylene, solutions having a polymerization initiator
(azobisisobutyronitrile) dissolved in monomer mixtures (see Table 1) were
added dropwise over a period of 6 hours. Postpolymerization was performed
for 2 hours to prepare the samples of copolymer (A) shown in Table 1.
TABLE 1
__________________________________________________________________________
Synthesis Example No.
1 2 3 4 5 6 7
__________________________________________________________________________
Monomer feed formulation
(parts by weight)
butyl acrylate
63.5 445 9.5 7.4 66.6 587 181
methyl methacrylate
389 23 457 447 400 -- 389
stearyl methacrylate*.sup.1
117 119 -- 117 118 -- --
acryester SL*.sup.2
-- -- 117 -- -- -- --
trimethylolpropane
-- 18.2 -- -- 6.0 18.2 --
trimethacrylate
TSMA*.sup.3 30.5 3.0 14.7 29.1 KBM 502*.sup.6
3.0 30.5
14.7
mercaptosilane*.sup.4
-- 11.8 12.5 12.0 KBM 802*.sup.7
11.8 --
18.0
AIBN*.sup.5 12.0 6.0 43.2 30.0 6.0 6.0 12.0
xylene 255 110 262 257 257 110 255
Copolymer (A)
number average
9,700 9,000 2,400 3,700 4,500 8,700 9,500
molecular weight (Mn)*.sup.8
molecular weight
1.9 3.4 2.4 1.8 1.9 3.0 2.0
distribution (Mw/Mn)*.sup.8
conversion to polymer
99 99 98 100 98 100 99
(%)
solids content in
70 85 70 70 70 85 70
resin (%)
__________________________________________________________________________
*.sup.1 Acryester S .RTM. of Mitsubishi Rayon Company Limited;
*.sup.2 C.sub.12 -C.sub.13 mixed alkyl methacrylate of Mitsubishi Rayon
Company Limited;
*.sup.3 methacryloxypropyl trimethoxysilane;
*.sup.4 mercaptopropyl trimethoxysilane;
*.sup.5 azobisisobutyronitrile;
*.sup.6 methacryloxypropylmethyl dimethoxysilane;
*.sup.7 mercaptopropylmethyl dimethoxysilane;
*.sup.8 measured by GPC.
SYNTHESIS EXAMPLE 8
A pressure-resistant reactor vessel equipped with a stirrer was charged
with 800 g of polyoxypropylene having an average molecular weight of 8,000
that had an allylether group introduced at 97% of all the terminals
present. Thereafter, the reactor was charged with 19 g of
methyldimethoxysilane and 0.34 ml of a solution of chloroplatinic acid
catalyst (i.e., a solution having 8.9 g of H.sub.2 PtCl.sub.6.6H.sub.2 O
dissolved in 18 ml of isopropyl alcohol and 160 ml of tetrahydrofuran).
Reaction was then carried out at 80.degree. C. for 6 hours.
IR spectrophotometry showed that the amount of residual hydrosilicon groups
in the reaction solution was negligible. Determination of silicon groups
by NMR analysis showed that the reaction product was polyoxypropylene
having about 1.7 units of terminal
##STR18##
groups per molecule.
SYNTHESIS EXAMPLE 9
The procedures of Synthesis Example 8 were repeated except that
polyoxypropylene having an average molecular weight of 6,000 that had an
allylether group introduced at 97% of all the terminals present was used
to make polyoxypropylene having about 1.7 units of terminal
##STR19##
groups per molecule.
EXAMPLES 1 TO 5 AND COMPARATIVE EXAMPLES 1 AND 2
The polyoxypropylene having an average molecular weight of 8,2000 that was
prepared in Synthesis Example 8 and each of the copolymer (A) samples
prepared in Synthesis Examples 1 to 7 were blended at a solids content
ratio of 50/50 and the compatibility of the two polymers in the uncured
blend was tested, the results of which are shown in Table 2.
The method of blending two polymers was a follows: to a solution of
copolymer (A) that was heated at 50.degree. to 60.degree. C.,
polyoxypropylene having reactive silicon functional groups at its
terminals was added in portions and the mixture was stirred until an
intimate blend was obtained. The blend was held at a predetermined
temperature and subjected to photometry in a selected glass cell for haze
measurement.
TABLE 2
__________________________________________________________________________
Haze after
Haze after
standing
standing
State immediately
overnight
at 50.degree. C. for
after mixing
at R.T.
14 days
Run No.
Copolymer (A)
(50.degree. C.)
(%) (%) Compatibility
__________________________________________________________________________
Example 1
prepared in Synthesis
Uniform and transparent
5 <10 good
Example 1
Example 2
prepared in Synthesis
" 22 14 "
Example 2
Example 3
prepared in Synthesis
" 5 <10 "
Example 3
Example 4
prepared in Synthesis
" 7 <10 "
Example 4
Example 5
prepared in Synthesis
" 9 <10 "
Example 5
Comparative
prepared in Synthesis
uniform but opaque
>90 separated
compatible
Example 1
Example 6 into two
at first but
layers later turned
incompatible
Comparative
prepared in Synthesis
separated into two
separated
separated
incompatible
Example 2
Example 7 layers into two
into two
layers
layers
__________________________________________________________________________
The data in Table 2 show that the blends using the v samples of copolymer
(A) prepared in Synthesis Examples 1, 3, 4 and 5 were uniform and
transparent and remained the same after storage at 50.degree. C. for 14
days. The blend using the sample of copolymer (A) prepared in Synthesis
Example 2 was also uniform and transparent and even after standing at
50.degree. C. for 14 days, it remained visually transparent although it
experienced a slight increase in haze.
EXAMPLES 6 TO 10 AND COMPARATIVE EXAMPLES 3 AND 4
The sample of copolymer (A) prepared in Synthesis Example 2 and the
polyoxypropylene (B) prepared in Synthesis Example 8 were blended in
varying proportions of from 100/0 to 0/100 so that the total amount would
be 100 parts by weight. To each of the blends thus obtained, dibutyltin
phthalate was added as a curing accelerator in an amount of 3 parts by
weight with respect to the solids content in resin. The mixtures were cast
into sheets having a thickness of 2 to 3 mm, which were cured at room
temperature for 7 days and subjected to a tensile test. The results are
shown in FIG. 1.
The tensile test was conducted with Dumbbell No. 3 (JIS K6301) at
23.degree. C. with tension applied at a rate of 200 mm/min.
EXAMPLES 11 TO 15 AND COMPARATIVE EXAMPLES 5 AND 6
The sample of copolymer (A) prepared in Synthesis Example 3 and the
polyoxypropylene (B) prepared in Synthesis Example 8 were blended in
varying proportions of from 100/0 to 0/100 so that the total amount would
be 100 parts by weight. To each of the blends thus obtained, dibutyltin
phthalate was added as a curing accelerator in an amount of 3 parts by
weight with respect to the solids content in resin. After addition of 15
parts by weight of a plasticizer, the mixtures were cast into sheets 2 to
3 mm in thickness, which were cured at room temperature for 7 days and
subjected to a tensile test as in Example 6. The results are shown in FIG.
2.
As is clear from FIGS. 1 and 2, the blends of copolymer (A) and
polyoxypropylene (B) exhibited, at all proportions, performance that was
better than that indicated by the additive curves obtained by connecting
the values of breaking strength and elongation of (A) and (B) taken
individually. Particularly, compositions having superior property to those
composed of a single ingredient are existed in wide range.
EXAMPLES 16 AND 17 AND COMPARATIVE EXAMPLES 7 AND 8
The copolymer (A) prepared in Synthesis Example 1 and the polyoxypropylene
(B) prepared in Synthesis Example 8 were blended so that the solids
content ratio in resin would be 65/35 (Example 16) and 50/50 (Example 17).
Using these blends, enamel was prepared in accordance with the paint
formulations shown in Table 3 below. To the enamel, 2.5 parts by weight of
dibutyltin phthalate was added per 100 parts by weight of the solids
content in resin. The mixtures were cast into sheets for a dry thickness
of 0.5 to 1.0 mm, and cured at room temperature for 7 days.
The resulting paint films were subjected to a tensile strength test and to
an accelerated weather test. The test results are shown in Table 3.
TABLE 3
__________________________________________________________________________
Example
Comparative
Example
Example
Comparative
Example 7
16 17 Example 8
__________________________________________________________________________
Formulation
Copolymer (A) prepared in Synthesis
100 65 50 0
Example 1
Polyoxypropylene (B) prepared in
0 35 50 100
Synthesis Example 8
Titanium oxide*.sup.1
40 40 40 40
Xylene 60 60 60 60
Dispersion stabilizer*.sup.2
0.3 0.3 0.3 0.3
Ultraviolet absorber*.sup.3
0.5 0.5 0.5 0.5
Antioxidant*.sup.4
0.5 0.5 0.5 0.5
Dibutyltin phthalate
2.5 2.5 2.5 2.5
Film characteristics
Breaking strength (kg/cm.sup.2)
120 60 40 12
Elongation at break (%)
2 210 350 120
Gloss retention in SWM*.sup.5
500 hr
97 95 95 0
1,000 hr
90 87 87 extensive
surface
cracking
2,000 hr
85 80 80
(partly
(good)
(good)
cracked)
__________________________________________________________________________
*.sup.1 CR90 (product of Ishihara Sangyo Kaisha, Ltd.)
*.sup.2 Byk P1043 (BykMallinckrodt Corp)
*.sup.3 Tinuvin 327 (CibaGeigy Ltd)
*.sup.4 Tinuvin 770 (CibaGeigy Ltd)
*.sup.5 Sunshine weatherO-meter
The data in Table 3 shows the dramatic increase in elongation that was
achieved by using blends of copolymer (A) and polyoxypropylene (B) as a
paint base. The data also show that such blends exhibited much improved
weather resistance as compared with the paint that employed
polyoxypropylene (B) as the sole resin component. The film formed from the
paint that used copolymer (A) as the sole resin component experienced
cracking on account of its hardness and brittleness but such problems were
absent from the blends of (A) and (B).
EXAMPLES 18 TO 21 AND COMPARATIVE EXAMPLES 9 AND 10
The copolymer (A) prepared in Synthesis Example 4 and the polyoxypropylene
(B) prepared in Synthesis Example 9 were blended in a solids content ratio
in resin of 60/40 (Example 18) or 50/50 (Example 19). The solvent was
distilled off in a rotary evaporator at 100.degree. C. under vacuum so as
to obtain solvent-free resins that were viscous, slightly yellow and
transparent.
To each of the resins, 2.5 parts by weight of dibutyltin phthalate, 2.0
parts by weight of an 1 aminosilane compound (A-1120, adhesion promoter of
Nippon Unicar Co., Ltd.) and 0.4 part by weight of water were added so as
to prepare samples of an adhesive, which were subjected to an adhesion
test (for its procedures, see below) using an aluminum substrate. The
results are shown in Table 4.
Samples of an adhesive were prepared in Examples 20 and 21 by repeating the
above procedures except that the copolymer (A) of Synthesis Example 5 and
the polyoxypropylene (B) of Synthesis Example 8 were used. The results of
an adhesion test conducted on these adhesive samples are shown in Table 4.
Preparation of Samples for Measurement of T-Shape Peeling Strength and
Tensile Test Method (according to JIS K 6854)
The surface of an aluminum plate (A-1050P A1 plate specified in JIS H 4000
that measured 200 mm.times.25 mm.times.0.1 mm) was lightly rubbed with
acetone and, using a spatula, an adhesive composition was coated in a
thickness of ca. 0.3 mm over an area of ca. 25 mm.times.100 mm. The coated
surfaces of two aluminum plates with an adhesive coating were bonded
together by means of a hand roller (5 kg) that was allowed to roll along
the length of aluminum plates without reciprocating. This roller operation
was repeated five times. The resulting sample was cured at 23.degree. C.
for day and aged by heating at 50.degree. C. for 3 days. The aged sample
was set in a T-shape in a tensile tester and pulled at a rate of 200
mm/min. The load under which the adhesive portion of the sample broke was
measured to determine the T-shape peeling strength of the sample.
Preparation of Samples for Measurement of Tensile Shear Strength and
Tensile Test Method (according to JIS K 6850)
The surface of an aluminum plate (A-1050P A1 plate specified in JIS H 4000
that measured 100 mm.times.25 mm.times.2 mm) was lightly rubbed with
acetone and, using a spatula, an adhesive composition was coated in a
thickness of ca. 0.05 mm over an area of ca. 25 mm.times.12.5 mm. The
coated surfaces of two aluminum plates with an adhesive coating were
bonded together by hand. The resulting sample was cured at 23.degree. C.
for one day with the bonded surfaces being fixed. The cured sample was
aged by heating at 50.degree. C. for 3 days and subjected to a tensile
test at a pull rate of 5 mm/min. The maximum load at which the adhesive
portion of the test piece broke was divided by the shear area to determine
the tensile shear strength of the sample.
TABLE 4
__________________________________________________________________________
Run No.
Comparative
Example
Example
Example
Example
Comparative
Example 9
18 19 20 21 Example 10
__________________________________________________________________________
Composition (parts by weight)
Copolymer (A) of Synthesis
100 60 50 -- -- --
Example 4
Copolymer (A) of Synthesis
-- -- -- 60 50 --
Example 5
Polyoxypropylene (B) of
-- -- -- 40 50 100
Synthesis Example 8
Polyoxypropylene (B) of
-- 40 50 -- -- --
Synthesis Example 9
Dibutyltin phthalate
2.5 2.5 2.5 2.5 2.5 2.5
Adhesion promoter
2.0 2.0 2.0 2.0 2.0 2.0
Water 0.4 0.4 0.4 0.4 0.4 0.4
Evaluation
T-shape peeling strength
1.0 10.8 9.0 12.4 11 3.5
(kg/25 mm)
Bonding strength (shear)
15 90 70 107 80 10
(kg/cm.sup.2)
__________________________________________________________________________
The data in Table 4 show that the adhesive employing the curable
composition of the present invention exhibited a good balance between
peeling strength and shearing bond strength, thereby producing a much
higher bond strength than the comparative adhesives employing either
copolymer (A) or polyoxypropylene (B) independently.
While the invention has been described in detail and with reference to
specific embodiments thereof, it will be apparent to one skilled in the
art that various changes and modifications can be made therein without
departing from the spirit and scope thereof.
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